Mini junk sail for multiple uses

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  • 01 Sep 2018 21:51
    Reply # 6649687 on 6642768
    Anonymous member (Administrator)

    Of, course, that extra rudder I sketched up looked like an accident waiting to happen, so now I have beefed it up  -  at least digitally…

    Arne


  • 31 Aug 2018 09:57
    Reply # 6647569 on 6642768

    This is good news. Seems that I can slip the sail ar least 15-20cm more forward. This should also improve the sheeting angle (and on the other hand make sitting on the foredeck (which she loves) more difficult for my daughter).

  • 31 Aug 2018 02:41
    Reply # 6647256 on 6645711
    Anonymous wrote:

    PS: I wouldn't worry too much about robbing the nice camber on one tack by increasing the balance. Paul Thompson in La Chica has proven that his ship still performs well on both tacks with 18-20% (?) balance. I know, I know  -  the myth of the bad tack is strong…

    Yes, the foresail with 20% balance and 12% camber, the so called bad tack is still the better tack. The mast is buried in the sail and the airflow apparently does not care.
  • 30 Aug 2018 12:37
    Reply # 6645711 on 6645672
    Anonymous member (Administrator)
    Jami wrote:

    Thanks again!

    Somehow I find it very difficult to accept an offset rudder. Would it really be necessary, do you think?


    No, not really. I was mainly thinking of the outboard engine and I wanted to avoid that it has to sit too much offset.

    Arne

    PS: I wouldn't worry too much about robbing the nice camber on one tack by increasing the balance. Paul Thompson in La Chica has proven that his ship still performs well on both tacks with 18-20% (?) balance. I know, I know  -  the myth of the bad tack is strong…

    Last modified: 31 Aug 2018 12:47 | Anonymous member (Administrator)
  • 30 Aug 2018 11:24
    Reply # 6645672 on 6642768

    Thanks again!

    Somehow I find it very difficult to accept an offset rudder. Would it really be necessary, do you think?

  • 30 Aug 2018 11:18
    Reply # 6645670 on 6642768
    Anonymous member (Administrator)

    From Jami's earlier postings it appeared that the sail-to-boat balance was OK until the boat started heeling. Since it was reported to be directionally unstable, I concluded that directional stability could be fixed by turning the original rudder into a skeg, by locking it, and more steering power could be gained with a new rudder. This may well be offset 20cm to keep it out of the slipstream of the old rudder.

    In case I have misunderstood, and the sail is simply sitting too far aft, the sailplane is drawn in its aft position and can be shifted quite a bit forward.

    Arne

    PS: I added numbers to that rudder sketch. Hopefully that will let you draw it up on a sheet of plywood or something.


    Last modified: 31 Aug 2018 10:49 | Anonymous member (Administrator)
  • 30 Aug 2018 09:15
    Reply # 6645579 on 6642768

    I aimed for max camber at thirty-something% from which the curve changes to straight quite fast. 

    EDIT: I don't know if this video gives a clue, whether I succeeded or not (see the broadseams and tucks).

    Last modified: 30 Aug 2018 10:09 | Anonymous member
  • 30 Aug 2018 08:53
    Reply # 6645575 on 6642768

    I forgot to say: is the camber too far aft in the sail? This is a common cause of excessive weather helm and poor performance. All the curvature should be in the forward half of the sail, with a straight run in the after half.

  • 30 Aug 2018 08:17
    Reply # 6645555 on 6642768

    I guess I knew all this deep down, but needed someone wiser and more stable to point it out... 

    A a matter of fact I was going to try to add a bit of forward rake. I have about 20mm to spare (by changing/taking off wedges) at the partners, which should add suprisingly lot some 8+ meters further up. The con is more weight at the bow, which already has more than I would like.

    At the moment I have about 10-12% of balance on the sail, and I think this affects the camber in an unpleasant way.

    The potential rudder issue has to wait for the winter anyway, so I have the autumn left to try things above waterline.

  • 30 Aug 2018 08:01
    Reply # 6645524 on 6644090
    Jami wrote:To be clear: this idea is only partly due to the trimming issues of my Galion. The multi-purpose minisail just popped up while I was thinking about this.

    Whether it would be wise to add a foresail or not (probably not), it seems like a valid plan to use a small sail as an anchor sail and to sail a dinghy, doesn't it?

    I would say that it's "probably not" in all three cases.

    Arne and I looked at the profile of the Galion 22 earlier, and thought that the rudder looked OK. If there's too much angle on the helm, then the sail is in the wrong place, and the right solution is to address this, not to add a complication in the form of another sail. Weather helm should only be a problem in the stronger breezes when you won't want the extra area of the second sail. Shift the existing sail forward temporarily by moving the halyard further up the yard and letting the tack go further forward, and see if this improves the helm. If it does, then the better major alteration to the boat would be to rake the mast forward, not to add a second rudder.

    Why would you want a riding sail? I don't, on a boat the same length but lighter. An anchor chum slows down the tendency to sail around at anchor.

    Junk rigged dinghies are fun in their own right, and a good way of first getting into JR, but adding junk rig to a cruising yacht's tender adds complication, and it doesn't get used very often, when the novelty has worn off. KISS. 

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